1. Field of the Invention
The present invention relates to a semiconductor light-emitting device and to a method for manufacturing such a device, and, in particular, to the shape of an envelope for enclosing the semiconductor light-emitting device.
2. Description of the Prior Art
A manufacturing process for a conventional semiconductor light-emitting device will now be explained.
FIG. 1, FIGS. 2A and 2B, FIGS. 3A and 3B, and FIGS. 4A, 4B are diagrams illustrating this manufacturing process. FIG. 1 is a diagram showing a plurality of semiconductor light-emitting elements mounted on and bonded to a lead frame.
FIG. 2A is a view of the upper surface of an envelope adjusting jig.
FIG. 2B is a longitudinal cross-section viewed along the line II B-II Bxe2x80x2 in FIG. 2A.
FIG. 3A is an upper surface view showing conditions after shape of the envelopes. FIG. 3B is a longitudinal cross-section viewed along the line III B-III Bxe2x80x2 in FIG. 3A.
FIG. 4A is a view of the upper surface of a completed conventional semiconductor light-emitting device. FIG. 4B is a longitudinal cross-section viewed along the line IV B-IV Bxe2x80x2 in FIG. 4A.
In FIG. 1, the reference numeral 8 designates a lead frame. A lead group made up of a pair of leads 9, 9xe2x80x2 is formed at a uniform spacing in the longitudinal direction of the lead frame 8. For example, the uniform spacing between adjacent lead groups is approximately 6 to 7 mm and the leads 9, 9xe2x80x2 are made up of Fe wires.
In FIG. 2A, the reference numeral 12 designates an envelope adjusting jig. A plurality of cavities 13 with circular lateral cross-sections and almost U-shaped longitudinal cross-sections is positionally arranged in a straight line at the same spacing as the lead groups on the lead frame.
First of all, as shown in FIG. 1, a semiconductor light-emitting element 10 is mounted on the upper end of one of the leads 9 in each of the lead groups on the lead frame 8. The upper surface of the semiconductor light-emitting element 10 and the other lead 9xe2x80x2 are electrically connected by a bonding wire 11.
Next, a light-transmitting resin such as a liquid mixture of epoxy resin, the leis filled into the cavities 13 of the envelope adjusting jig 12 shown in FIGS. 2A and 2B, then the lead groups of the lead frame 8 are inserted into the respective cavities 13 and the light-transmitting resin is thermally cured.
As shown in FIGS. 3A and 3B, the mounted section of the semiconductor light-emitting element 10 of the lead groups and the upper end section of the bonding wire 11 and the leads 9, 9xe2x80x2 are sealed in an envelope 14 formed by the light-transmitting resin. Subsequently, as shown in FIGS. 4A and 4B, each of the lead groups is separated from the lead frame 8 at the part shown by the broken lines in FIG. 3B with a cutter to complete the semiconductor light-emitting device.
Recently, there have been demands for semiconductor light-emitting devices with a high output. Also, it is commonly known that the diameter 14D of the light-emitting device 14 should be made as large as possible to successfully obtain high output.
However, for good production efficiency in this manufacturing method for the conventional semiconductor light-emitting device, the spacing between the lead groups is set so that it is possible to form about 10 to 30 semiconductor light-emitting devices using one lead frame, and, in addition, the diameter 13D of the envelope depends on the spacing of the lead groups on the lead frame. For this reason, there is the problem that even when it is desired to increase the diameter of the envelope to obtain high output, this diameter is limited by the spacing of the lead groups. In addition, when the spacing of the lead groups is increased to provide an envelope with a large diameter, the number of semiconductor light-emitting devices obtained from one lead frame is reduced. This results in the problem of poor production efficiency.
Accordingly, an object of the present invention is, with due consideration to the drawbacks of such conventional devices, to provide a semiconductor light-emitting device from which high output can be obtained by increasing the spacing between the lead groups on a lead frame, and to provide a method for manufacturing such a semiconductor light-emitting device.
The present invention provides a semiconductor light-emitting device, as one of preferred embodiments, formed on a same lead frame on which a plurality of semiconductor light-emitting devices are formed in a straight line at a uniform spacing, said each semiconductor light-emitting device comprising:
a plurality of lead means placed in parallel;
semiconductor light-emitting means mounted on the upper end of one of said leads;
bonding wire means for electrically connecting the semiconductor light-emitting means and the upper end of another lead means with a long axis and a short axis; and
envelope means formed from a light-transmitting resin for sealing said semiconductor light-emitting means, said bonding wire, and the upper end of said lead, provided with a non-circular lateral cross-sectional surface structure,
wherein when observed along a direction in which the plurality of light-emitting devices are mounted on the same lead frame, a curvature of the lateral direction of said envelope is smaller than a curvature of the vertical direction of said envelope.
In the semiconductor light-emitting device above, for the lateral cross-section of said envelope is shaped by being cut one part of said envelop in a straight line along the direction in which the plurality of light-emitting devices are mounted on the same lead frame.
In addition, the lateral cross-sectional shape of said envelop means is an ellipse shape in the semiconductor light-emitting device described above as a preferred embodiment.
Moreover, the number of said lead means is two, and the number of said semiconductor light-emitting means is one in the semiconductor light-emitting device described above as a preferred embodiment.
Furthermore, the number of said lead means is three, and the number of said semiconductor light-emitting means is two in the semiconductor light-emitting device described above as a preferred embodiment.
The present invention also provides a manufacturing process for a semiconductor light-emitting device, as another preferred embodiment, formed on a plurality of lead frames, on each of the lead frames a plurality of semiconductor light-emitting devices are formed, comprising steps of:
a process for forming the lead frame with a plurality of groups of side-by-side leads positioned in a straight line at a uniform spacing;
a process for forming an envelope adjusting jig whereon cavities at a plurality of points are positioned on the non-circular lateral cross-sectional surface structure, with a long axis and a short axis, so that when observed along a direction in which the plurality of light-emitting devices are formed on the same lead frame, a curvature of the lateral direction of said each envelope in the same lead frame is smaller than a curvature of the vertical direction of said each envelope, and the short axis is positioned on a straight line at a spacing which is the same spacing as the group of leads;
a process for mounting the semiconductor light-emitting element on the upper end of one lead of the group of leads and for connecting the semiconductor light-emitting element and the upper ends of the other leads of the group of leads with bonding wires;
a process for filling the light-transmitting resin into the cavities of the envelope adjusting jig;
a process for immersing the semiconductor light-emitting element, the bonding wire, and the upper end of the leads in the light-transmitting resin in the cavities and sealing this part with the light-transmitting resin; and
a process for removing the lead frame from the envelope adjusting jig and separating each group of leads from the lead frame.
In the manufacturing process for a semiconductor light-emitting device described above, further comprising a process for offsetting the lead frames alternately at a suitable length only, so that the lead frames are respectively parallel.